export class ByteUtils {
    static isNull(obj) {
        for (var a in obj) {
            return false;
        }
        return ture;
    }

    static hexStrToBytes(str) {
        var pos = 0;
        var len = str.length;
        if (len % 2 != 0) {
            return null;
        }
        len /= 2;
        var hexA = new Array();
        for (var i = 0; i < len; i++) {
            var s = str.substr(pos, 2);
            var v = parseInt(s, 16);
            hexA.push(v);
            pos += 2;
        }
        return hexA;
    }

    static bytesToHexStr(bytes) {
        var str = '';
        for (var i = 0; i < bytes.length; i++) {
            var hexStr = bytes[i].toString(16);
            if (hexStr.length == 1) {
                hexStr = '0' + hexStr;
            }
            str += hexStr;
        }
        return str;
    }

    static stringToUtf8Bytes(str) {
        var bytes = new Array();
        var len, c;
        len = str.length;
        for (var i = 0; i < len; i++) {
            c = str.charCodeAt(i);
            if (c >= 0x010000 && c <= 0x10FFFF) {
                bytes.push(((c >> 18) & 0x07) | 0xF0);
                bytes.push(((c >> 12) & 0x3F) | 0x80);
                bytes.push(((c >> 6) & 0x3F) | 0x80);
                bytes.push((c & 0x3F) | 0x80);
            } else if (c >= 0x000800 && c <= 0x00FFFF) {
                bytes.push(((c >> 12) & 0x0F) | 0xE0);
                bytes.push(((c >> 6) & 0x3F) | 0x80);
                bytes.push((c & 0x3F) | 0x80);
            } else if (c >= 0x000080 && c <= 0x0007FF) {
                bytes.push(((c >> 6) & 0x1F) | 0xC0);
                bytes.push((c & 0x3F) | 0x80);
            } else {
                bytes.push(c & 0xFF);
            }
        }
        return bytes;
    }

    static utf8BytesToString(arr) {
        if (typeof arr === 'string') {
            return arr;
        }
        var str = '', _arr = arr;
        for (var i = 0; i < _arr.length; i++) {
            var one = _arr[i].toString(2);
            var v = one.match(/^1+?(?=0)/);
            if (v && one.length == 8) {
                var bytesLength = v[0].length;
                var store = _arr[i].toString(2).slice(7 - bytesLength);
                for (var st = 1; st < bytesLength; st++) {
                    store += _arr[st + i].toString(2).slice(2);
                }
                str += String.fromCharCode(parseInt(store, 2));
                i += bytesLength - 1;
            } else {
                str += String.fromCharCode(_arr[i]);
            }
        }
        return str;
    }
}
